Legacy LED driver solutions that achieve a suitably high power factor often include single-stage flyback and buck converters using electrolytic capacitors. However, as modern LED illumination systems are configured to produce more and more light output (e.g., lumens), the operating temperature in the illumination system (e.g., lamp) increases, and the increased temperature of operation begins to play a factor in reliability of the aforementioned electrolytic capacitors. Additionally, the aforementioned electrolytic capacitors in combination with the aforementioned legacy single-stage converters suffer high LED ripple current.
Even in cases where legacy LED illumination drivers employ two stages, such legacy two-stage converters have included an electrolytic capacitor to decouple the first and second stages. Although the second stage can be configured to regulate the current to achieve low ripple (e.g., due to the presence of the electrolytic capacitor in these legacy implementations), the combination is not suitable for the needed combination of high temperature operation and long life.
Moreover, trends in LED illumination demand ever more control of light output under various conditions such as when connected to an electronic transformer, and/or for dimming, and/or for operation in environments exhibiting extremely high temperatures and/or extreme temperature changes.
Therefore, there is a need for improved approaches.